Flutter – Barebones, Basic Good Looking Login Page, with Routing

Getting up and running with anything new can be challenging. Frameworks are no different. Sometimes we know what we want, but it can be challenging transfering that to the new framework. By building a Login Page, we stand the chance of playing with many cool swiss-knife-like features in Flutter.

I’ve been doing Angular and Django for some time, both rock solid frameworks for building web applications. However, getting started with Flutter (Dartlang) presents different ways of thinking and going about seemingly simple tasks.

If you recently got started with Flutter (I got started about 2 days as at writing this), you might have many questions, at least regarding how all these ‘Widgets’ fit together.

In building a simple looking Login Page together, I’m sure it should help you get started on the right foot.

So here we go.

In this article, expect to learn at least these:

Doing something like a routing table

Creating forms

Switch from one page to another (navigation)

At the end of this and the subsequent articles, you’re building what’s below.

Flutter Login Page

Deal!

New Project

flutter create login_app

Done. Project created. Then

cd flutter && flutter run

At this point, if your Android SDK and others are well setup, you should have no issues at all.

In my case, after setting my Android environment right, I’m using my phone as the emulator.

If you don’t know how to setup your Android SDK and emulator etc, or how to setup Flutter in general, check this article:

Flutter new project (click to view)

We should see something like the above in either our emulator on PC or on our Android Phone screen. We’re good to know if you do.

Brick by Brick

In the Flutter project directory, open the lib/main.dart file and delete everything in. You should end up with something like this:

Flutter Clean Slate

What a sense of calmness and peace!

By the way, I use vscode. Just saying.

Now it’s time for you and I to build the Login Page, brick by brick, on code line at a time. You can do this. I personally couldn’t find any line by line resource online explaining how each part fits together. So you welcome!

Imports

Flutter has got inputs, just like your Angular (Javascript ES6) or your Django (Python). Almost the entire beefy part of Flutter Components Widgets are within this module? package? file?. No idea what the right word would be. But well, imports exists in Flutter too.

Perhaps think of it as the import { } from '@angular/core' thing.

Let’s import our primary package:

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// If using VScode with the flutter plugin,

// autocompletion with imports exist, like

// in Angular.

import'package:flutter/material.dart';

.....

With that import in place, you can say, the whistle has been blown!

Bootstrapping

Trust me, I do not fully comprehend the mechanism behind the scenes, but there’s something like the entry point of every flutter app. Think the main.ts file of Angular? Maybe.

From this point in code, is where the entire application is bootstrapped. In Flutter, it goes like this:

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import'package:flutter/material.dart';

voidmain()=>runApp(newMyApp());

Everything is a Widget in Flutter! Duh

We pass the MyApp widget (in fact, it’s a class which extends from a StatelessWidget, you guessed right, Class) into the runApp() widget, bootstrap the application for good.

Wanna try and run the current code we have and see what happens?

Flutter has something they call, Hot reload. Unlike Angular’s CLI restarting of the entire Angular application when you make changes, Hot Reload allows changed part of the code to swap in live into the emulator seamlessly.

So if you changed a button color from blue to red in Angular, the entire application is restarted.

With Hot Reload in Flutter, everything will stay the same, but only the button color would be, say, reloaded to see the change in color.

It’s pretty cool.

Whether you tried the two-line snippet up there or not, the obvious truth is, Flutter will scream at you. MyApp()class widget doesn’t exist, yet!

So how do we fix things?

MyApp() For The Win

Take a look at this:

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classMyAppextendsStatelessWidget{

// This widget is the root of your application.

@override

Widget build(BuildContext context){

// some flesh of code to be put here.

}

}

Now you know MyApp(), right? Say hi then!

Did I know what a StatelessWidget was basically? Nope. But I learned quickly as I was writing this article by just hovering over the class in vscode.

StatelessWidget

In short, use StatelessWidget for situations where the state of your application won’t change.

Do you understand? You don’t? Good. Let’s move on.

What is the purpose of @override?

Dart @override

Now you get the idea? You can hover on the rest of the classes and methods to read about what they are. I find most of these on-hover tips much more useful, because right in code, I get to learn what’s going on.

Finally, Something Real

The code below achieves what’s in the image next below this snippet

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import'package:flutter/material.dart';

voidmain()=>runApp(newMyApp());

classMyAppextendsStatelessWidget{

// This widget is the root of your application.

@override

Widget build(BuildContext context){

returnnewMaterialApp(

title:'Flutter Demo',

home:newScaffold(

appBar:newAppBar(

title:newText(

'Welcome Home',

),

),

body:newCenter(

child:newText(

'Welcome Home',

style:newTextStyle(

fontSize:22.00,

fontWeight:FontWeight.bold,

),

)

),

),

);

}

}

Basic Flutter App

There’s a lot packed within the above code snippet. A lot. You can hover over each class to learn the technicalities along with the allowed properties on each class, and methods if any.

But I’ll do a quick overview:

Widget build(BuildContext context), in English, is saying, whatever comes next, I want you to process that into the page (context). What comes next?

MaterialApp() widget. This widget comes with in-built long haul batteries to help us seamlessly build Material Design apps, such as changing the theme, colors, and more, the material design way

MaterialApp() Widget

The home and title widgets of MaterialApp comes in handy next. The title is what you see when on the title bar of your application when in Recent Apps mode on your phone.

The home widget is the “the route that is displayed first when the application is started normally”. Since we’ve not seen routing yet, the app will always begin with what’s put at the home widget

The Scaffold() widget, is well, a Scaffold. Allows us to quickly build mobile-like UIs without writing much. It gives us the AppBar and body Widgets. Hurray.

AppBar & Text Center

Pretty cool right?

What’s Next?

Do you now get a high level picture of what we’re doing here?

It’s the same concepts we know, presented in a different format. You’re not writing your code in JS, CSS and HTML to mix and blend eventually. No!

Rather, Flutter puts all three combined in one.

Saw how the Text()widget was styled? Boom!

In the next article, we consider routing. Adding a routing table, and moving from a page to the other.